RU Pat. No 2,336,005 published on 20 Oct. 2008 under indexes MΠ A44C27/00, B44C5/06, B44F9/04, C04B30/00, C03C6/02, B28D5/00 claims the mixture of the raw materials for manufacturing the parts of jewellery intended to substitute the precious stones. The mixture comprises the crushed silicate glass and wastes of rubies and/or sapphires, and/or emeralds, and/or alexandrites, and/or noble spinels, and/or euclase, and/or topazes, and/or aquamarines, and/or heliodors, and/or garnets, and/or amethysts, and/or hyacinths, and/or cordierites, and/or turmalines, and/or rock-crystals, and/or smoky quartz, and/or chrysoprase, and/or carnelian. In the invention, the silicate glass with the melting temperature of 500-950° C. is used. The composition material is produced by stacking together the wastes of precious and semiprecious stones using the silicate glass with very low melting temperature. Parts produced by this procedure have low mechanical strength. They cannot be used in serial production as their appearance cannot be reproduced. Due to the difference in the coefficients of thermal expansion of the silicate matrix and fillers made of precious stone wastes, the resultant composite material has low thermal shock resistance. Above all, a convenient and inexpensive technology of jewellery manufacturing “casting with stones” cannot be applied to such materials due to the low melting temperature of the silicate glass.
RU Pat. 2,162,456 published on 27 Jan. 2001 with indexes MΠ C04B5/14 and C01B33/113 outlines the manufacturing of synthetic material with the noble opal structure. Synthetic material is produced by the following stages: 1. preparing the monodisperse suspension of amorphous silica with globule sizes of 140-600 nm.; 2. precipitating, layer by layer the precipitate and drying at 100-150° C. for 10-30 h, after that, further drying the precipitate at a pressure of 1-10 Pa.; 3. after drying, annealing the precipitate at the temperature of 350-400° C. and the pressure of 15-45 MPa in the atmosphere of water vapor and tetraethoxysilane; and 4. filling the precipitate with silica sol and heat-treating at 400-600° C. for 1-2 h.
This method is very difficult, labor- and time-consuming, the product cost is very high. In addition, by this method, obtaining materials of various phase assemblage, structures and colours is impossible. The main drawback of this material is that it is very brittle and cracks during dehydration, which occurs quickly especially upon heating. It is worth noting that the processes are rather intensive at as low temperature as 100° C.
RU Pat. No 2,215,455 published on 10 Nov. 2003 with indexes MΠ A44C17/00, C30B31/02, C30B33/02 presents the method for colouring natural and synthetic gemstones. The method is intended for colouring the colourless and pale blue sapphires, colourless topazes and quartz. The method consists of placing the grinded gemstones into a thin cobalt oxide powder comprising a mixture of CoO and Co2O3 in the ratio of 1:1 mixed with ZnO in the ratio of 1:(0.25-3). The mixture is heat-treated in the oxidizing conditions at 900-1250° C.
The parts prepared by said method are coloured only on the suRUace. Their additional grinding and polishing is impossible because the thin coloured layer becomes damaged. This method provides only blue colouring, other colour tints cannot be achieved.
RU Pat. No 2,253,706 published on 20 Jan. 2005 with indexes MΠ C3029/20, C30B28/00, C30B31/02, C30B33/02 outlines the jewellery material—synthetic polycrystalline corundum “Mariite” and its method of synthesis. The material consists of alumina, colour dopants and paraffin wax used as a binder. The colour dopants are molybdenum, wolfram, neodymium, erbium, chromium oxides. The production of the material used as parts for jewellery is made by forming the mixture with the use of molding machines under a pressure of 4 atm. followed by the subsequent firing in furnaces of continuous or periodic action. Then the coloured translucent potsherd is polished with diamond powder. This method ensures only production of semitransparent material; transparent material cannot be produced by this method, which significantly reduces the variety of the final articles. In addition, the obtained materials are of the limited range of colours: there are no blue, green, yellow, brown materials. The nature of the binding agent—paraffin wax—prevents material operation at elevated temperatures.
It is well known that glass-ceramics with near zero thermal expansion coefficients are produced by the controlled crystallization of solid solutions with β-quartz (β-eucryptite) structure in glasses of the lithium aluminosilicate system. This method is used in production of coloured transparent thermal shock resistant kitchen ware, cooking tops, windows of metallurgic and heating furnaces. Researches from Corning Inc., USA, developed glass compositions converted to glass-ceramics by heat-treatment and coloured to various tints of yellow, brown and purple colours. U.S. Pat. No. 3,788,865, MΠ C03C10/14, published in 1974, describes production of transparent coloured glass-ceramics, containing β-eucryptite crystals and coloured with the following dopants: V2O5, MnO, Cr2O3, Fe2O3, CuO, NiO and ZnS. However, the resulting materials have a relatively low hardness, which is an important disadvantage for jewellery materials. U.S. Pat. No. 5,491,115, published on 13 Feb. 1996 with indexes MΠ C03C010/14, C03C010/12, outlines production of purple-red and violet colour in transparent thermal shock resistant material. However, all these materials have a relatively low hardness, which is an important disadvantage for jewellery materials.
RU Pat. No 2,42,6488, on 20 Aug. 2010 with indexes MΠ A44C17/00, A44C27/00, the prior art, presents the material with high hardness, chemical resistance and colour resistance against thermal shock. This is a synthetic transparent, translucent or opaque nanocrystalline composite material for jewellery based on at least one of the following nanosized oxide or silicate crystalline phases: spinel, quartz-like phases, sapphirine, enstatite, petalite-like phase, cordierite, willemite, zircon, rutile, zirconium titanate, zirconium dioxide, with a content of ions of transition, rare earth elements and noble metals in an amount from 0.001 to 4.0 mol %.
Despite its unique properties, the material does not have an ultralow thermal expansion coefficient (CTE) (below 30·10−7 K−1) which means that it does not have the required high thermal shock resistance. The lack of the required high thermal shock resistance impedes the rapid machining, in particular, the laser suRUace treatment, and making holes with lasers. The method of “casting with precious stones” cannot be used because the material that contains crystalline phases with high thermal expansion coefficient can crack during thermal cycling. Furthermore, its melting temperature range of 1570-1640° C., which complicates refining and homogenization of glass using the standard glassmaking equipment and require high energy consumption.
Thus, among the analogues and the prototype there is no material that would meet all the requirements of modern jewellery.